5–4
2. Check the seals. After long use, the lower seal may wear. The HoneyCombe
®
wheel will then ride on the inner layer of the seal material. Since this is not as
slippery as the outer layer, the wheel will not turn easily. Check the condition of the
lower seal. The surface of the seal should be smooth. If the seal is very worn, you
will be able to see some of the inner layer of seal material. If the seal must be
replaced, please contact the factory for instructions. See section 5.10, Checking the
Drive Motor, Wheel and Seals.
5.7 CHECKING THE HEATING ELEMENTS
This service procedure involves an electrical hazard. Service work
should only be done by an electrician who has been qualified by
Munters.
1. The heating elements are located near the intake for the reactivation air. See Fig.
1–4.
2. To check the elements, you must remove them. Turn off the power to the unit!
Remove the inlet grill for the reactivation air. The element assembly is held in place
with one bolt at the corner of the reactivation inlet duct. Remove the bolt and slide
out the element assembly.
3. Check the resistance across each of the heating elements using an Ohmmeter. The
resistance across each element should be 8Ω to 19Ω. Take your measurements
at the incoming wire leads. If you find an infinite resistance, the element has
developed an open circuit, and must be replaced. A faulty heating element assem-
bly must be replaced as a unit.
4. Each of the power wires for the elements includes a fusible link. Once one of these
links opens, it will cut off power to the element. Check across each fusible link with
an Ohmmeter. A failed link will appear as an open circuit.
5. Model HC-150I only – Check for a problem with the thermistor (TSE1) for the power
controller (SSP1) If this thermistor open-circuits or shorts, the SSP1 will not pro-
duce any output for the heating elements.
5.8 CHECKING THE THERMISTOR
(Model HC-150I only)
1. A thermistor is a type of temperature sensor. This unit has one thermistor to sense
the temperature of the heating elements (TSE1)
2. Because of the way this part operates, it is difficult to check it with a volt-ohmmeter.
The thermistor may fail in either a shorted or an open-circuit condition. Either
condition will turn off the solid-state power controller (SSP1), so the heaters will not
operate. The easiest way to diagnose the problem is to substitute a new part.
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